The inventor of the present invention proposes a bearing device for an axle shown in FIG. 12. In the bearing device for an axle shown in the figure, a hub wheel 1 is jointed with a shaft 7 by a constant velocity joint 3 in a state the hub wheel 1 can be tilted.
A shaft end in a vehicle inner side of a hollow shaft 12 of the hub wheel 1 is bent and deformed in a radially outward direction so as to constitute a caulked portion 12a, which is caulked on an outer end face of an inner ring 25 of a double row rolling bearing 2. The inner ring 25 is preloaded by the caulked portion 12a and also is fitted so as not to come off from the hub wheel 1.
An outer ring 31 of the constant velocity joint 3 comprises a cup-shaped cylindrical portion 35 to store tilt movement guiding elements therein, and a shaft portion 36 which is inserted into the hollow shaft 12 of the hub wheel 1 in a small diameter portion of the cup-shaped cylindrical portion 35 and fitted by a spline fitting so as not to be rotated in a circumferential direction.
The caulked portion 12a of the hollow shaft 12 and a vehicle outer side are fitted in a manner of being sandwiched from an axial direction by the cup-shaped cylindrical portion 35 of the constant velocity joint 3 and a snap ring 50 in a section C shape arranged in a peripheral groove 36p on the vehicle outer side of the shaft portion 36, thereby the outer ring 31 of the constant velocity joint 3 is combined with the hub wheel 1.
In such a combination manner, when the snap ring 50 is inserted into the peripheral groove 36p in a state of leaving a required gap G1 in the axial direction, the outer shaft 36 is inclined to rattle in the axial direction with respect to the hollow shaft 12, which is caused by the gap G1. Under the circumstances, the outer ring 31 of the constant velocity joint 3 cannot be stably located with respect to the caulked portion 12a of the hollow shaft 12
As an idea for stabilization of the location of the constant velocity joint 3, it is suggested that the snap ring 50 is inserted into the peripheral groove 36p in a manner that the gap G1 is not generated so as to prevent the rattle.
However, such a manner of insertion makes it uneasy to insert the snap ring 50 and also to combine the outer ring 31 of the constant velocity joint 3 with the hub wheel 1.
Continuously, if the snap ring 50 is inserted with an excessive strength, a compression load affects on the hollow shaft 12 in the axial direction, thereby the caulked portion 12a of the hub wheel 1 is compressed and deformed, and then an excessive load is imparted to the double row rolling bearing 2. By this action, the double row rolling bearing 2 is excessively pressurized, and a rolling feature of the double row rolling bearing 2 is reduced. In response to that, the outer ring 31 of the constant velocity joint 3 has to be combined with the hub wheel 1 under required conditions, which is a hassle.
Therefore, a main object of the present invention is to provide a bearing device for an axle which is capable of maintaining an appropriate level of preload with respect to a double row rolling bearing, and stably locating an outer ring of a constant velocity joint with respect to a caulked portion of a shaft end in a vehicle inner side of a hollow shaft of a hub wheel, while easily combining the outer ring of the constant velocity joint with the hollow shaft.